Scanning and Synchronization to the Downlink in Initial Scanning

Subscriber Station (SS) are designed to scan their frequency lists for active downlink channel right away upon installation or following any period of signal loss. In case of signal loss, the SS will store operational parameters of the last signal and will attempt to restore the connection.

After obtaining a channel with a valid downlink signal, the SS will try to synchronize the PHY by listening for DL-MAP management messages. The SS will continue to listen for DL-MAP management messages and in the case of missing DL-MAP messages the SS will repeat the scanning and synchronization process.

WiMAX Network Entry and Initialization, part 2.

The network entry process can be separated into a few phases. Within each phase, particular MAC management messages  are exchanged among Base Station (BS) and Subscriber Station. On the establishment of process, the SS scans individual DL channels searching in favor of the DL-MAP and DCD messages broadcasted by the BS.

Using these messages, the SS get synchronize with the BS and obtains DL paremeters. As successfully synchronized, the SS wait for the UL-MAP and UCD messages to acquire UL parameters.